In 1966, Brooker founded Procol Harum with his friend Keith Reid.[10] "A Whiter Shade of Pale" is the worldwide hit for which Procol Harum is best known, but Brooker's melancholic vocals and emotive, eclectic piano playing were a key part of Procol's musical mix for the entire course of the band's career. In the early years Brooker, Hammond organistMatthew Fisher and Trower were the guiding musical forces behind the band, but after disparities in style became too much and Fisher and Trower left, Brooker was the clear leader until the band broke up in 1977. Brooker started a solo career and released the album No More Fear of Flying in 1979.

The same year, Brooker joined friend and neighbour Eric Clapton's band. With Brooker in the lineup, they released the studio album Another Ticket. Clapton fired the entire band in 1981, but he and Brooker have remained good friends since, and were for many years neighbours in the Surrey Hills. Brooker has joined Clapton for several one-off benefit gigs over the years. Brooker sang lead vocal on the Alan Parsons Project song "Limelight", on their 1985 album, Stereotomy. Brooker sang the lead vocal of the song "No News from the Western Frontier", a single taken from the album Hi-Tec Heroes by the Dutch performer Ad Visser.

A new incarnation of Procol Harum, led by Brooker, has continued touring the world, celebrating its 40th anniversary in July 2007 with two days of musical revels at St John's Smith Square in London. Brooker also toured with Ringo Starr's All-Starr Band in 1997 and 1999, and he was also a member of Bill Wyman's Rhythm Kings for several years, appearing on three of their albums and touring with the band. On 28 September 1996, as the Gary Brooker Ensemble, he organized a charity concert to raise funds for his local church, St Mary and All Saints, in Surrey. The resulting live CD of the concert, Within Our House, originally released on a fan club CD in a limited run of 1000 units, has since become a collectable recording. His guests and supporting artists included Dave Bronze, Michael Bywater, Mark Brzezicki and Robbie McIntosh.

On 28th October 2009, Brooker was presented with a BASCA in recognition of their unique contribution to music.[11]

In May 2012, Procol Harum were forced to cancel the remainder of their dates in South Africa after Brooker fractured his skull following a fall in his hotel room. The fall came on Brooker's 67th birthday. The band was part of the British Invasion Tour of South Africa along with the Moody Blues and 10cc.[12] He recovered sufficiently for the band to undertake an extensive US tour with Yes and to play concerts in Europe in 2013, several with symphony orchestras.

Personal life

In July 1968 Brooker married Françoise Riedo ("Franky"), a Swissau pair, whom he met circa 1965. The couple have no children.[13][7]